Door latch mechanism



7 Sheets-Sheet l H. W. SANFORD DOOR LATCH MECHANISM Flled Feb 25 1942 May 7, 1946.

y 1946. H. w. SANFORD 2,399,708

DOOR LATCH MECHANI SM Filed Feb. 25, 1942 '7 Sheets-Sheet 2 y 7, 1946. H. w. SANFORD 2,399,708

DOOR LATCH MECHANISM I Filed Feb. 25, 1942 7 Sheets-Sheet 3 I 'I;IIIIIIIIII H. W. SAN FORD DOOR LATCH MECHANISM Filed Feb. 25, 1942 7 Sheets-Sheet 6 y 1945- H. w. SANFORD 2,399,708

DOOR LATCH MECHANISM Filed Feb. 25, 1942 7 Sheets-Sheet 7 atented May 7, 1946 DOOR LATCH MECHANISM Hugh W. Sanford, Knoxville, Tenn, assignor to The Sanford Investment Company. Wilmington, Del., a corporation of Delaware Application February 25, 1942, Serial No. 432,341

40 Claims.

This invention relates to improvements in door latch mechanisms for drop bottom conveying equipment, particularly for the doors of drop bottom mine cars.

Automatic drop bottom cars of the types used heretofore have had provision for controlling the dropping oi. the doors by latch bar mechanism located outside the car and required special end sill structure at the end of the car where the latch bar mechanism was located, which was objectionable and expensive. Furthermore, the lateral projection of the latch bar from the car made it possible for obstructions alongside the track to raise the latch bar and dump the lading where not desired.

It has been proposed to provide separate latch mechanisms for the respective doors, so that the doors may be dropped in any desired order, but this requires a separate latch mechanism for each door. While this eliminated the projecting latch bar at the rear end of the car, this mechanism is expensive, and by projecting beyond the confines of the car, it is liable to be bent and knocked out of shape when the car is wrecked or run into the ribs.

In one such prior construction, latches are provided for the respective doors of a three-door car, which latches are located underneath transverse protective plates adjacent the axles. Such multiple latches are expensive, and projecting below the horizontal level of the bottoms of the doors and also below the end-sill structures, they are subject to injury or displacement in the event of wreckage of the car. Furthermore, the distance from the latch moving device located on the track and the pivots of the latches, must be perfectly adjusted. It would be very diilicult to maintain this adjustment and relative positioning of the parts in practice. Furthermore, there is no provision for the hand release of any of the doors, that is often desirable.

Mine cars that travel on tracks during a considerable period of service naturally are subject to much wear particularly on the treads of the wheels and on the axle journals, which may result in lowering of the car frame from its initial relation as much as of an inch. An device, therefore, that is used for disengaging the latch hooks from a point beside the track must be capable of accommodating both old and new cars in service and subject to such variation. Furthermore, the wrecking of the cars may cause bending of the frame and lowering of the end-sill structures with consequent variation of the distance between the supporting hook and the top of the rail. These several possibilities require substantial flexibility in a design that is to knock the latches for release thereof in a practical manner and to work efliciently for all such conditions.

The object of this invention is to improve the construction of door latch mechanisms which may be released automatically, Particularly for a multiple door mine car or other conveyance, wherein the forwardrdoors are released for dis charge into the bin as soon as the rearward door is released, in 1-2-3 order from front to rear of the car, by relatively simple and practical construction that will fulfill the requirements of service, whereby th latch bar mechanism may be removed entirely from outside the rear end of the car, and whereby the end-sill structures of both ends 01 the car can be made of duplicate pattern.

For multiple door coal mining cars, it is cheaper and simpler to use a single latch mechanism for the rear door which will control the dropping of the doors in 1-2-3 order, but for other conveying equipment, buckets and some types of latch vehicles other than coal mining cars that are contemplated within this invention, it may be more desirable to provide a separate latch mechanism for each door, even when multiple doors are used in a receptacle, as well as for the door of a single-door receptacle, which may be provided readily with thi invention.

The automatic drop bottom mine cars generally in use heretofore have had the rear door latched by a single book. Since it was possible for obstructions alongside the track to rais the latch lever mechanism on the rear end of the car inside the mine or at a point where dumping of the lading was not desired, it has been found desirable to provide special locking devices for holding the latch lever bar down until release is desired, but this was undesirable because it required special release of this safety locking device with loss of time. This objection is obviated in the present invention by the provision of double latch hooks each of which supports the door independently of the other, so that if one should be released accidentally, the other latch hook would still hold the door in closed position until the car reaches the dumping position. This latch mechanism also facilitates the use therein of additional latch hooks, if found desirable, which could be readily released when the car reaches its dumping position, and the character of the hooks and of their mounting and location facilitates manual release thereof when desired.

In embodying my invention in pract al st ture, I have provided latch mechanism for supporting the free edge of the rear door, or the free edge of any desired door, with provision for moving the latch mechanism from its latched position as by means located at the track at least partially beneath the car, to release the door automatically as the car passes over said means adjacent the point of dumping. Since the latch is located preferably in protected position with its lower edge above the lowermost portions of the car doors and end-sills in the same longitudinal vertical plane, provision is made for raising the releasing device into position for knocking engagement with the latch to release the latter automatically as the car reaches its dumping position. Thi may be accomplished by operating the releasing means by an attachment on the car. Where the force applied to the releasing means is not sufficient to knock the latch out of its engaged position beneath the free edge of the door, provision may be made for raising the door slightly to relieve the latch of the weight thereof long enough to unlatch the door, when the door is permitted to drop in the usual manner.

I have shown the invention in a preferred embodiment, together with modifications thereof, in the accompanying drawings in which:

Fig. l is a side elevation of a mine car and trackshowing the invention applied thereto;

Fig. 2 is an enlarged side elevation of a portion thereof including the rear end of the car;

Fig. 3 is a longitudinal sectional view therethrough;

Fig. 4 is a similar view enlarged and showing the latch releasing mechanism;

Fig. 5 is a transverse vertical section therethrough;

Fig. 6 is a longitudinal section through a portion of the car showing a modified form of latch releasing mechanism;

Fig. '7 is a longitudinal sectional view through another form of mine car having separate latches for the respective doors;

Fig. 8 is a transverse sectional view therethrough on the line 88 of Fig. 7;

Fig. 9 is a detail longitudinal sectional view through a portion of mine car with a further modified form of latch mechanism applied thereto;

Fig. 10 is a similar view showing this form of latch mechanism applied to intermediate doors thereof;

Fig. 11 is a transverse sectional view on the line l|-l| of Fig. 9;

Fig. 12 is a detail sectional view of the latch shown in Fig. 9, substantially on the line |2l2 therein;

Fig. 13 is a similar view showing the released position of the latch;

Fig. 14 is a detail sectional view showing another modified form of latch mechanism;

' Fig. 15 is a transverse sectional view therethrough on the line Iii-I5 of Fig. 14; and

Fig. 16 is a vertical section of a further modified form of latch mechanism having an electromagnetic release thereof.

The invention is shown as applied to a drop bottom mine car adapted for the conveying of coal or other loose lading from a receiving point to a pit or other point of discharge. The mine car is shown generally of the type set forth, for instance, in my prior patent, No. 2,001,471, granted May 14, 1935, representing a four-wheel to travel on a track formed by a pair of rails designated generally R.

The general structure of the car comprises side and end walls I and 2, respectively, the side walls I rising from a pair of oppositely disposed side sills 3 connected together at the ends of the car by means of combined end-sills and bumpers designated generally 4. The side and end sills 3 and 4 constitute the frame structure of the car for supporting the lading body of the car.

The car i supported upon wheels 5 and axles 6 connected with the side sills 3 by axle boxes 1. The flaring sides I of the body are cut away to receive the wheels, which are deeply inserted therein beneath wheel hood coverings 8. Opposite hood coverings 8 are connected together by means of a combined tie plate and shroud 9 which extends over the adjacent axle 6.

The car is shown as of the character provided with three drop bottom doors adapted for discharge in 1-2-3 order from front to rear of the car, which door are designated respectively It, II and I2. The forward door I0 is pivotally supported on a hinge rod l3, while each of the middle and rear doors H and I2 is slidably and pivotally mounted on a hinge rod l4, extending between opposed boxes 1, with the extreme forward edge of said door projecting laterally from the hinge rod and arranged to support the free edge of the next forward door. Thus upon release of the rear door it may drop sufficient to drag and move bodily rearward, thereby releasing the free edge of the middle door which will likewise move downward and rearward releasing the free edge of the forward door. This occurs usually justbefore the car reaches the bin and permits dropping of the forward door for discharge of the lading as soon as room enough is provided in the bin therebeneath, the other doors dropping in succession during forward movement of the car over the bin, in 1-2-3 order from front to rear of the car.

After dumping in passing over the bin, the doors are adapted to be closed by the usual door-closing rails located in the track, said doors having indentations l5, to ride thereon, which successively swing them into their closed positions. The doors are pushed forward into tightly engaged suppported positions by wedge blocks l6, having upwardly and forwardly inclined front faces in position for engagement by lugs II attached to the free edge of the rearward door l2 and projecting therefrom, as shown in Figs. 3 and 4. As the rearward door l2 swings to a closed position. the lugs I! ride up the inclined faces of the wedges I6 and force the doors into closed supported relation.

As shown in Figs. 1 to 6, provision is made for latching the free edge of the rearward door l2 for thereby holding the doors I0, H and I2 in their closed positions, retaining the lading in the car until the latching means is released for dumping. For this purpose latches l8 and I8 (Fig. 5) are provided adjacent the rear end of the car pivotally supported by a shaft 19, extending transversely thereof on which said latches are loosely mounted for freedom of movement relative to each other. Although a, single latch may be provided for the door at the center thereof, 1 have shown latches adjacent opposite sides of the door.

Each of the latches has a concave seat 20, formed therein in position to engage a latch hook 2! attached to the free edge of the rearward door mine car having three drop bottom doors, adapted 7 I! to support said rearward door. As shown in Fig. 4, the seat 20 is located on the opposite side of the vertical plane passing through the axis of the shaft is from the door i2, so that the weight of the door and the lading thereon tends to maintain the latched relation without any tendency for this weight to push the latch to one side. This is particularly true because of the concave shape of the seat 20 engaged by the convex end of the latch hook 2|, whereby any movement of the latch tending to release the door must raise up the free edge of the door.

Each of the latches l8 has a lateral pin 22, attached thereto and projecting through a slot 23 in the adjacent portion of the end-sill 4, so that a lever can be inserted over said sill, beneath the pin 22, for the manual release of said latch.

A coiled spring 24 is interposed between the inner face of the end sill 4 and the latch l8,

being seated in a recess 25 therein, tending to help to return said latch to a position where it will engage and support the latch hook 2|. The lower end portion of each latch i8, I8 has a lateral boss 26 provided with an upwardly inclined forward face tending to guide the latch hook 2| to its seated position and for pressing the latch to one side by the latch hook as the latter is moved upward after discharge of the lading. The boss 26 and the inclined face thereof, in the form shown, constitute latch actuating or release means on the conveyance for movin the latch when said boss is moved from externally of the car. i

As shown in Figs. 4 and 5, the latches 8 are interposed between the free end of the rearward door I2 and the adjacent end-sill 4, beneath a guard plate 21, and are disposed wholly above the lower edge of said end-sill or bumper and also above the lower portion of the rear door in protected positions. This prevents disarrangement of the latches or accidental injury thereto in the event of wreckage of the car as frequently occurs, thus insuring adequate protection of the latches to maintain the same in proper operative positions. 7

The tripping mechanism for the latches l8, l8, includes lever bars 28, 28' (Fig, respectively, fixed to a transverse shaft 29 mounted in suitable boxes 36 beneath the rails R. The upper free end of each of the lever bars, which is designated 3| in Fig. 4, is arranged in position to engage the angular face of the boss 26 on the corresponding latch l8 when said lever bar 28 is in raised position. The upward swinging movement of the lever bar 28 is limited by a flexible device 32, such 'as a chain or the like, one end of which is attached to the free end of the lever bar while the opposite end is attached to a fixed support 33 beneath the track. The downward swinging movement of the lever bar 28 is limited by a stop 34 secured in fixed position relative to the track. It will be evident that a single lever bar 28 will be provided if the door has only one latch l8, and the number of lever bars will correspond preferably with the number of latches.

As shown in Figs. 4 and 5, the shaft 23 has an upstanding lever arm 35 journaled thereon for freedom of movement relative to the shaft, and extending in position to engage a tripping lug 45 hereinafter described. An arm 36 extends substantially horizontally from the shaft 29 beside the lever arm 35, said arm 36 likewise being loosely journaled on the shaft 29.

A seat 31 is rigidly fixed to one side of the arm 36, shown as formed by welding a bracket to said arm, and receives therein one end of a coiled compression spring 38, the opposite end of wihch is received in a spring seat 33 likewise secured to the adjacent face of the lever bar 28. A bolt 40 extends through the spring seats 31 and 38 and through the coiled spring 38 for limiting the separating action therebetween. The spring and bolt 38, 46, constitute a lost motion connection between the arm 36 and the lever bar 26, tending to move the latter in response to upward swinging movement of the arm 36 from the dotted line to the full line position in Fig. 4.

A bracket 4| is rigidly secured by welding or otherwise to the pivoted end of the arm 36, upstanding therefrom, and having one or more set screws 42 extending adjustably therethrough in position to form an adjustable abutment in the path of movement of the arm 35 toward the left in Fig. 4 and to vary the upwardly extending position of said arm.

A bracket 43 extends laterally from the shaft 29 in the opposite direction from the arm 36 and on the opposite side of the lever arm 35 therefrom, said bracket 43 being rigidly secured by welding or otherwise to the lever arm 35 for unitary rotation around the shaft 29. The outer end of the bracket 43 carries a counter-weight 44 constructed to keep the upright lever arm 35 in correct position for engaging the lug 45 when the lever arm 28 is resting on the stop 34 below it, and also to bring back the lever arm 35 to its engaging position after the car has passed over the tripping device in the reverse direction. In order for the car to pass over the tripping device in the reverse direction, it is necessary to make the lever arm 35 so that its engagement with the lug 45 will rotate it around shaft 29 without disturbing anything else. Then, when lug 45 has passed over, the lever arm 35 comes back upinto its proper position for engaging the lug 45 for the unlatching operation.

Normally the weight of the lever bars 28, 28, would cause them to rest against the stops 34, in the dotted line position in Fig. 4. In this position of the lever bars, the lever arm 35 is in the right hand dotted line position marked "normal" in Fig. 4, where it would be held by the counterweight 44, in position for unlatching. The limit of the swinging of the lever arm 35 in its normal position is controlled by the lever arm 36 and set screws 42. The position of the lever arm 36 is regulated by the action of the spring 38 and by the bolt 46. When arm 28 is resting on stop 34, the compression spring 36 forces arm 36 down until the nut on the bolt 40 stops further relative motion of the two elements; and at this stage the position of arm 35 is controlled by the adjustment of screws 42. In other words, arm 35 is as high up as it can go under the influence of counterweight 44 when the other parts are functioning in the manner described. The weight of the bar 28 when resting on the stop 34 acts through the spring 33 to produce a limited downward movement of arm 36, which movement, in turn, is transmitted to the arm 35 through screws 42.

For operating the latch release mechanism, I have provided a tripping lug shown at 45, which is secured to the bottom of the side sill 3 at a predetermined definite distance from the face of the latch l8, which lug 45, has a gradually inclined forward lower face 45' in position to engage the upstanding lever arm 35, to move the same gradually from the right hand Normal dotted line position in Fig. 4 to the full line position therein, as the car passes over the tripping mechanism toward the left in the direction indicated by the arrow in Fig. 4. This will have the effect of swinging the arm 36 upward from its dotted line position to its full line position, first, compressing the spring 38, and then acting therethrough to lift the lever bars 28 and 28' to their full line position in the path of the lugs 26 on the latches l8, the extent of the upward movement being limited by the chains 32.

The lug 45 has an abrupt rear end face 45" which permits quick release of the lever arm 35 when said lug has passed thereover, when the lever arm returns to its dotted line position and releasing the lever bars 28 for very rapid dropping by their weight onto the stops 34, thu allowing the lever bars to clear the end sill and bumper, after knocking back the latch hooks the required distance.

I have shown in Fig. 4, by a dotted line P, the relative path of movement of the upper end 3| of the lever bar 28, with respect to the position of the car shown, notwithstanding that the tripping mechanism is in a fixed position while the car moves thereover. The lug 45 is arranged in such position that its face 45' will engage the lever arm 35 when the lever bar 28 is in relative position a in Fig. 4. The upper end 3| will then travel up the path P to the full line position in Fig. 4, and remain at its high point until after the latch l8 has been moved free of the door. Then the lever bar will swing down to the position b.

When the lever bars 28 are raised to their full line positions in Fig. 4, the end faces 3|, thereof engage the bosses 26 on the latches I8, I8, forcing the latter backward against the tension of the springs 24 as well as against the action of gravity on the latches tending to hold them forward, thus releasing the latch arms 2| from within the seats 28 and allowing the rearward door to drop down at once to a point where the returned latch hooks will no longer engage the lugs 2|. In practice the door drops two or three inches and the latches swing back promptly, but cannot re-engage hooks 2|. The door then slides along on a slide, provided between the rails until it has passed entirely over the tripping mechanism and until it has come to the bin, and until it has gone far enough along over the bin to find room for full dropping.

This has the effect described above, of releasing the other doors and allowing the forward door to drop open as soon as a space is clear therebeneath in the pit. The angular relation of the face 3| to the forward face of the boss 26 when these parts ar brought into engagement, will insure the positive release of the latches l8 and prevent any tendency for the lever bar 28 to slip down on the hook without pushing the latch backward toward the end sill 4 sufficiently to insure positive unlatching of the door, regardless of whether or not the hook is jammed and regardless of the speed of the car. After the lever bars 28 have dropped sufilciently to disengage the latches l8, l8, these latches will return automatically to their latching position shown in Fig. 4, by the action of the springs 24 and by the force of gravity, subject to the limitation imposed by the engagement of pins 22 with the bumper face, and subject also to the position of the lugs 2| on the dropped door. If the door is only allowed to drop a couple of inches, the latches would first come in contact with lugs 2|, but below the seats 20, so as not to cause re-latching. Then later, when the door drops further, the latches will be forced by gravity and by the springs to their maximum forward position, namely, the position shown on Fig. 4, and when in this position it will relatch the dropped door as soon as it is raised by the door raising device.

As will be evident from the path P in Fig, 4, the lowest bottom portion of the drop door in line with the latch, passes over the top of the face point 3 when the lever bar is in its lowered position on the stop 34. The lug 45 is so arranged that it raises the face point 3| higher than the bottom of the door for release of the latch but in such fashion that it will never collide with the bottom of the door. This path P is also such that the end face 3| shall not come in direct contact with the back of the bumper sill, which is accomplished by having the lever arm 35 reach the end of the bottom surface of the lug 45 before the face 3| of the lever bar 28 has come very close to the back of the bumper sill.

In the event that wear occurs on the wheels or axles, which might cause a lowering of the car frame, this would lower the position of the lug 45, relative to the lever arm 35, but it would operate the tripping mechanism in the same manner as described.

The lever bars 28 have a limited upward motion, and when the car is new there is a substantial clearance above the face of the lever bar and the bottom of the door when the lever bar is as high as it can go. If the lug 45 should drop lower, due to wear of the wheel treads or axle journals or bearing boxes-a wear that will never exceed one-half inch-the coil spring 38 of Fi 4, or'a spring having like effect in other forms, will permit the lever arm 35 to be rotated counterclockwise more than normal by virtue of the lug 45 being lower due to the wear, as indicated by the dotted line position W in Fig. 4. The engaging position of lever bars 28 with the hooks would not be affected thereby except to the extent that the right-hand end of the car is lowered closer to the track by this wear. Ample clearance is provided for this, as will be noted, and it is a desirable part of the construction. Furthermore, if the right-hand end of the car should droop down before wear occurs-due to some abnormal wreck or strain on the framethere is still no danger of any normal deflection of the car frame causing the top of the lever bar 28 to come into solid contact with the bottom of the door.-

A modified form of tripping mechanism is shown in Fig. 6 in which a lever bar 28a is pivotally mounted at one end on a transverse shaft 29a while its opposite end is in position to engage a latch |8a constructed and mounted in the manner described above in connection with the latch I8, for holding the door |2a in its latched position. The lever bar 28a is rigidly fixed to the shaft 29a, but has an offset end bracket 39a in the path of movement of an adjustable set screw 38a secured to an arm 36a to which the counter-weight is connected through a link 44a. The arm 36a is rigidly fixed to, and extends laterally from, the lever arm 35a.

The lever arm 35a has a plunger 48 slidably mounted in a socket 49 therein bearing against.

a compression spring 50, housed in the socket and confined by an adjusting screw 5|. The outward movement of the plunger is limited by pins 52 attached to the plunger 48 and extending through slots 53 in opposite sides of the socket 49.

The operation of this form will be obvious from the foregoing description. When the car passes over the releasing mechanism, the lug 4511 attached to the side sill of the car will engage the plunger 48 and act thereon to swing the lever 35a to the left in Fig. 6, thus raising the lever bar 28a from its full line to its dotted line position for releasing the latch I821, and thereby releasing the doors for dropping. The spring pressed plunger 48 will allow operation of the latch releasing mechanism positively regardless of variations that may occur between the car and the releasing mechanism due to the normal wear on the wheels or axles.

The dotted line P represents the relative path of movement of the tripping bar to the car. The face of the plunger 48 has just engaged the sloping front of lug 45a and the lever bar 28a is starting in its lowest position, as indicated at a. As the car moves along and as the force of the inclined surface of the lug 45a is exerted on the plunger 48, the action will start up which will raise lever bar 28a into the upper dotted line position for knocking the latch hook. The lever bar will be held in this upper dotted line position as long as the plunger 48 rides against the level under face of the lug 45a, as indicated by the line P. Furthermore, the lug 45a will be made the proper length so as to release the lever bar 28a for dropping before it can possibly touch the back of the end sill. v

This form is particularly advantageous because it is adjustable for height by an adjustment of the screw 5| which will vary the projection of the plunger 48 to a degree corresponding with the location of the car sill relative thereto. This adjustment may be made after the apparatus is in place, so that it will be accurate. Furthermore. the construction is desirable because it permits the car to be oscillated back and forth at the dumping bin by the haulage locomotive, as is desirable at times in order to shake down coal that may be sticking to the sides. Even if the upright lever arm or the plunger thereof, is in engagement with the lug on the side sill of the car during this oscillating motion thereof, the spring cushion acting on the plunger will prevent the car from being raised up on the track.

The use of the cushion spring acting on the plunger never applies suiflcient pressure to the lug on the car sill to raise the car oif the rails,

because it will yield before lifting the car. This spring will nevertheless have sufllcient tension so as to cause the rotary motion of the lever arm 35a to raise the lever bar 28a to its unlatching position when properly operated by the lug 45a on the car sill.

The plunger arm shown in Fig. 6 may be used, if desired, in the tripping mechanism shown in Fig. 4, while retaining with the latter the flexibility obtained by the spring connection 38, and the adjustability obtained by the screws 42.

The construction shown in Figs. 7 and 8, illustrates the manner in which the latching mechanism may be provided for the respective doors of the car, as illustrated applied to the central door llb and the rear door l2b, each of which has its forward edge pivotally mounted and has the rear edge thereof latched in a closed position, the latch for the rearward door In being shown as constructed and operated in the manner described above in connection with the latch IS.

A latch I8!) is provided for engagement with a latch hook Zlb attached to the free edge of the door ll b. The latch l8b is pivotally suspended from a transverse rod l9b which may extend transversely of the car and support on the opposite end thereof a similar latch for the door,

adjacent the opposite side of said door, in the event that a pair of latches is provided therefor, as described above, which may be individually or simultaneously released as desired. The latch lib and rod l9b are mounted beneath a combined tie plate and shroud 9b which cover the adjacent edges of the doors llb, l2b, as well as the axle of the car. The supporting rod is thus protected against minor deflections of the shroud that might be due to the lading, A spring 241) bears against the latch l8b tending to hold the same in position for latching the door closed.

This provides progressive unlatching action for the respective doors of the car as it moves along the track, by means of one unlatching device, in the event that separate latching of the doors be desired, even though it does increase the cost thereof somewhat. However, it is practical for use in some conveying devices other than mine cars, such as high swinging railroad cars, trailers or other vehicles and for the several receptacles of a conveyor.

When latches are thus provided for the respective doors of the conveying device or car, it will be evident that tripping lugs 45b would be provided in proper positions for the dropping thereof, being spaced in predetermined positions from the engaging faces of the latches according to the lengthof the latch bars, as will be evident from Fig. 7.

While the tripping mechanism shown in Fig. 4 or in Fig. 6 might and preferably is used for unlatching a central or intermediate door, the tripping mechanism illustrated in Fig. 7 utilizes a lever bar 28b pivotally mounted on a shaft 29b, on which shaft a lever arm 35b is journaled in position for upstanding relation in the path of the tripping lug 45b. The lever arm 35b is held in aid upstanding position by a counterweight 44b suspended from an arm 43b attached as by welding or otherwise to a face of the lever arm 35b. A set screw 38b is adjustably connected with the arm 43b and extends therefrom into bearing relation with a track 39b oflset from the pivot end of the lever bar 28b, to transmit swinging movement from the lever arm 35b toward the left in Fig. '7, to the lever bar 28b to raise the latter from a reclining position on stop 34b to its tripping position as shown in full lines in Fig. '7.

Another form of the invention is shown in Figs.-

9 to 13, in which the latches are positioned so as to operate transversely of the car frame instead of longitudinally thereof as described above. This is particularly advantageous when the latches are installed under the combined tie plate and shroud for the axle, but this form does not require the release of the latch by a blow imparted directly thereto from tripping mechanism beneath the track.

Figs. 9 and 11 show the invention applied to the rear door of the car, designated I20, the forward doors of which may be connected together for release in 1-2-3 order as described above in connection with Figs. 1 to 3 or may be separately latched as desired. The door l2c has a latch hook Zlc projecting from the free end thereof either at the middle, if one latch i provided, or adjacent each opposite side if a plurality of latches are provided, as shown. The latch is designated l8c and is pivotally supported on a bolt l9c mounted on the end wall 20 and end sill 4c of the car. The latch I is constructed of substantlally L-shape provided with a seat 200 at the free end thereof. The latch is mounted on the pivot lac for swinging movement between the positions shown in Figs. 11, 12 and 13, for thereby holding the latch hook Me or releasing the same as shown, the swinging movement of the latch I80 in the opposite directions being limited by stops 55 and 56 secured to the forward face of the end sill lo.

With this form of the invention, it is necessary that the door be lifted to release the latch, for which purpose I have provided a lifting pad 51 attached to the underface of the door 120 in position for engagement by a tripping device 58. The tripping device 58 i in the form of a ramp, having inclined upper surface 58 in position for engaging the lifting pad 51 to raise the door l2c as the car passes thereover. The tripping device 58 is pivotally supported at 60 with a counterweight 6| suspended thereby, as shown in Fig. 9, and normally rests in an angular position further to the right than is illustrated in Fig. 9. However, when the car moves over the tripping device, the engagement of the pad 51 therewith swings said device on the pivot 80 until the shoulder 62 thereof engages a stop 88 in the position shown, which causes the door I20 to be lifted appreciably, sufllcient to release the latch in the manner shown in Figs. 11 to 13.

Fig. 12 shows the parts in their latched relation, with the latch hook 2lc resting in the seat 200 of the latch. However, when the door is lifted up by engagement of the pad 51 with the inclined surface 59, the latch hook Zlc is raised from the position shown in Fig. 12 to the position shown in Fig. 11, thereby engaging the edge 84 of the latch I80 and forcing the latch to swing in a counter-clockwise direction about the pivot I90. This movement is sufllcient to release the latch hook 2lc from the seat 280, and when the lifting pad 51 has passed over the lifting device 58 immediately after the position shown in Fig. 9, the door drops immediately.

The latch hook 2lc will then fall therewith from the position shown in Fig. 11 to the position shown in Fig. 13, continuing down with the dropping of the door. The hook I8c will swing also after release of the latch hook 2lc from engagement of the edge 64, but the latch hook 2lo will fall below its latched position before the latch l8c can swing to the left far enough to engage under the hook, and thus the free edge of the latch will fall against a side face of the latch hook Zlc or pass thereover, and thus does not prevent the dropping of the door. Gravity acts to swing the door downward faster than the latch, whereby the door is released, but if the door should engage a lump of coal, for instance, in the track as it passes thereover, it would not be released quick enough to prevent its engagement by the latch.

This form of latch mechanism might be applied also readily to drop bottom conveyors, and if it should be desired to prevent the tripping of a. door, this could be accomplished readily by swinging the dropping ramp 58 to the right to such an extent that it would not engage the lifting pad 51 to operate the latch release as the car passes thereover,

The latch I8c is shown in Fig. as applied for latching one of the intermediate or forward doors of the car or other conveyor, engaging and supporting latch hook 2Ic thereof. In this position the latch is located beneath the combined tie plate and shroud 90 that extends over the space between the doors and over the axle therebetween.

In Figs. 14 and 15, the latch or latches [8d are constructed for supporting a door In substantially in the manner described above in 0011- nection with Fig. 4. However, provision is made in this form of the invention for lifting the door by means of a lifting pad 86, attached to the underface thereof in position to ride over a lifting ramp 81 for raising the door from its latched position, as shown in Fig. 14, which ramp has an abrupt shoulder at its forward end for quick dropping of the door upon release of the latch.

Provision is made for withdrawing the latch from its latched position, for which purpose I have provided here a brush 68 of the character of ordinary wire brushes of sufficient width and length to engage the free end of the latch I8d, as the car passes thereover, to sweep this latch back to the position shown in Fig. 14, after the lifting of the door by the ramp 6'! until the car has moved past the ramp suiilciently to let the door drop quickly free of the latch. A brush 68 is provided for each latch lBd of the door, and may be mounted beside the ramp 61.

Instead of withdrawing the latch in the manner described, provision may be made for positive withdrawing action thereof, as shown in Fig. 16, by means of a solenoid 10, having a plunger ll pivotally connected with the latch Me for positive withdrawal of said latch upon energizing of said solenoid after lifting of the door free thereof in the manner described above. The latch is returned to its engaged position by a spring 12 surrounding the plunger 'H and bearing thereagainst.

Provision may be made for energizing the solenoid at the desired point by the location of contacts respectively on the car and beside the track in position for engagement as the car reaches the dumping position, substantially in the manner set forth in Duncan patent No. 2,138,695.

As shown, the solenoid, one or more of which may be provided according to the number of latches used on the door, may be housed within the bumper structure out of the way, or in other convenient position on the conveyor body. Such a solenoid-operated latch may be particularly advantageous for the type of conveyor using drop bottom conveying buckets arranged for the selective discharge of the lading into bins whenever desired by an operator. Provision may be made for actuating the solenoids selectively under control of the operator, and in a similar way, the operator can control the discharge of the lading through any of the doors by the mechanical devices described above.

In any event, the latch hooks are shown as mounted in protected'positions on the car and of such simple construction that use of this latch mechanism does not complicate the car construction or render it appreciably more expensive. The latch hooks are located entirely above the lower edges of the car frame where there is no danger of injury or dislocation thereof in the event of a wreck. Even where attachments are applied to the doors to facilitate the release of the latches, these are not located in positions where there is danger of destruction thereof in the event of a wreck. It will be noted that the lifting pads applied in some forms of the invention, are above a plane passing from the lower edge of an end sill to the bottom of a wheel.

I claim:

1. In a dumping conveyance, a lading body including side and end frame structures and wall structures supported thereby, a drop bottom door within the lower portion of the body for supporting at least a part of the lading thereof and mounted on the body for downward movement relative thereto to release the lading, the combination of latch means on the body for supporting a free edge portion of said door when closed and movable to release the door for dropping, said latch means being so constructed and arranged that no part of it extends laterally outside of the space between upwardly extending planes passing at the outer edges of the side frame structures and along the outer surfaces of the side wall structures in door supporting position of the latch means, and said latch means being arranged entirely above the lower edge of the frame structure in protected position thereby and disposed between the free edge portion of said door and the adjacent end frame structure, and actuating means connected with the latch means in position to be engaged by tripping mechanism externally of the conveyance, said tripping mechanism being located substantially entirely between said upwardly extending planes and above the lower edge portion of the frame structure.

2. In a dumping conveyance, a lading body and a frame structure having a lading bottom including a drop bottom door, latch means for holding the door closed and movable to release the same for dropping, said latch means bein located wholly above the horizontal plane of the upper lading surface of the lowest portion of said drop bottom door in closed position and wholly above the horizontal plane of the portion of the frame structure which lies substantially in the same longitudinal vertical plane as the latch means, and said latch means comprising a latch member having a portion arranged for latching engagement with the door, and latch actuating means connected with the latch member, said latch actuating means being located substantially entirely within the space between upright planes at the outer edges of the frame structure and extending upwardly at the outer faces of the'lading body and including a portion in position for accessibility from 'beneath the conveyance for movement of said latch member to release the door for dropping during rectilinear movement of the conveyance.

3. In a dumping conveyance adapted to be mounted on a trackway and including a frame structure having a transverse forward end portion, and a drop bottom door, latch means for holding the door closed and movable to release said door for dropping, said latch means including a supporting portion in position to engage the free edge portion of said door and an actuating portion accessible from beneath at least a part of the conveyance, said actuating portion being connected with the supporting portion and facing toward the front of the conveyance and spaced from the door when latched in position to be engaged for moving said supporting portion to release the door, said supporting and actuairing portions of the latch means being located wholly above the portion of the transverse forward end portion of the frame structure lying in the same longitudinal upright plane.

4. In a drop bottom mine car, the combination of a frame structure having side and end sills, and a lading bottom supported thereby, said lading bottom including a drop bottom dumping door extending between the side sills, means pivotally supporting said door at one edge thereof, a latch in position for supporting the opposite edge of said door and movable to release the same for dropping, said latch being mounted between said door and the adjacent end sill and located wholly above the lower edge of the end sill in position for protection against injury and from accidental release in abnormal conditions, said latch having an abutment thereon facing toward the opposite end of the car and spaced from the door in latched position, said abutment being accessible from beneath the car for movement of the latch to a released position during rectilinear movement of the car.

5. In a drop bottom mine car adapted to be mounted on track rails and having side sills and rear and front end structures surrounding the area through which the lading of the car may be dropped, the combination of at least one drop door which when closed supports at least part of the said lading to prevent its discharge through th said area, the said door when closed having a portion extending below. the bottom level of an end structure to permit engagement of said portion of the drop door with door closing means located between the track rails, latch means mounted for movement longitudinally of the car and housed from contact with the lading by being located in a space between the rear end of the said door and the adjacent end structure, and the said latch means engaging and supporting the free edge portion of the said closed drop door when the latch is in its forward position and releasing the said door for dropping when moved from its forward to its rearward position, and the said latch means being protected from obstructions along the track by portions of the end structure extending lower than the bottom portion of the said latch means in the same longitudinal vertical plane when the latch means is in its doorsupporting position, and the said latch means being unlocked and always free to swing from its door-supporting to its non-supporting position whenever suflicient pressure is applied against its forward lower portion, and said latch means including an actuating portion located above the lower edge of the end structure in the same longitudinal vertical plane intermedi ate the front and near end structures and facing toward the front end of the car, and spaced from the door for actuating the latch means.

6. In a drop bottom mine car adapted to be mounted on track rails and having side-sill means with transverse end-sill structures connected therewith and cooperating to form a. load-supporting car-frame structure, and a drop door within the frame structure for supporting at least a part of the car lading, the combination of a latch for supporting a free edge portion of said door when closed, said latch having its lowest portion when in door supporting position above the portion of the lower edge of the endsill structurelying in the same longitudinal upright plane, means mounting said latch for movement in a direction lengthwise of the car to release the door for dropping, said latch having an actuating portion facing toward the front of the car and spaced from the door when closed in position to be accessible from beneath the car when the door is-closed.

'1. In a drop-bottom mine car, a supporting frame-structure including longitudinally extending side-sill structures and transversely extending end-sill structures, a drop-bottom doorstructure located between opposed side-sill structures and being sealed therewith when the door is in its closed position, latch means which is mounted to move backward and forward longitudinally and which in its forward longitudinal position has a portion which will be below and in a position to engage and support the said drop-bottom door-structure approximately at its rearward end when the said door-structure has been raised for latching slightly above its closed position, and the supporting portion of the said latch means being forward of said rear end-sill structure, and the said latch means passing from its door-supporting position to its door-releasing position by a longitudinal movement rearwardly, and actuating means connected with the latch means and facing toward the front of the car in spaced relation from the adjacent door-structure in position to be engaged by tripping mechanism externally of the car to release the door-structure, the said latch means and actuating means being so located vertically in respect of the end-sill structures that, when the closed door is being supported by the latch means, the lowest portions of the latch means and actuating means lie above portions of the said end-sill structures which lie in the same longitudinal vertical plane whereby they are protected by the said end-sill structures from injury otherwise incident to movements of the car along the track.

8. In a dumping conveyance, a frame structure having a lading bottom including a drop bottom door, a plurality of latches in position to engage an edge of said door for holding the door in closed position, said latches being spaced apart transversely of the conveyance, means pivotally mounting said latches for freedom of swinging movement longitudinally of the conveyance and relative to each other, said latches being located wholly above the horizontal plane of the lowest portion of the frame structure, each of said latches having an actuating portion above the lower edge of the frame structure in the same longitudinal vertical plane and facing toward the front end of the conveyance and spaced from the door when latched in position to be engaged for movement of the latch to a releasedposition during rectilinear movement of the conveyance.

9. In a dumping conveyance, a frame structure having a lading bottom including a drop bottom door, a plurality of latches in position to engage an edge of said door for holding the door in closed position, said latches being spaced apart transversely of the conveyance an appreciable distance, and means mounting said latches for movement independent of each other lengthwise of the conveyance toward and from the door, each of said latches having an actuating portion above the lower edge of the frame structure in the same longitudinal vertical plane and facing toward the front end of the car and spaced from the door when latched and accessible from beneath the conveyance for release actuation'during rectilinear movement of the conveyance.

10. In a dumping conveyance, the combination of supporting wheels, a frame structure carried by the wheels and including longitudinally extending side sill structures and transversely extending end sill structures, said side sill structures being mounted between oppositely disposed wheels, a drop bottom door structure located between opposed side sill structures, latches mounted on the frame structure in protected positions wholly above the lowermost edges of the end sill structures in the same longitudinal vertical plane for movement backward and forward relative thereto and in position to engage and support a free edge portion of said door structure in closed position, said latches being spaced appreciable distances on opposite sides of the longitudinal center line of the door structure adjacent and inwardly of the side sill structures and coacting to support the edge portion of the door structure at laterally spaced points, each of said latches having an actuating portion thereon in the same longitudinal vertical plane and facing toward the front end of the conveyance and spaced from the door structure when latched in position to be engaged and which, when the door is supported in its closed position, projects underneath and supports an adjacent portion of the door structure, and the said actuating portion being accessible from under the conveyance for engagement to trip the latch.

11. In conveying mechanism, the combination with a trackway, a dumping conveyance movable along the trackway and including a frame structure having transverse end-sill structure and having a lading body with a drop bottom door, latch means for holding the door in closed position and movable to release the door for opening, and latch release means on the conveyance connected with the latch means and located in a shielded area between the outer edge portions of the frame structure and above the lower edge thereof, of tripping mechanism including means mounted at the trackway directly under the conveyance when the conveyance passes thereover and movable into said shielded area into actuating engagement with the latch release means for actuating said release means to trip the latch.

12. In a dumping conveyance, the combination of a frame structure including transverse endsill structure and having a lading body includ- .ing a drop bottom door, latch means for holding the door in closed position, said latch means being located wholly above the lowest portion of the end-sill structure in the same longitudinal vertical plane of the conveyance, said latch means including an actuating portion accessible from beneath the conveyance, and means located at the trackway and movable in an upward direction for engaging said actuating portion to release the latch means, said engaging means being arranged in such position that the closed door of the conveyance will pass directly above the same.

13. In conveying mechanism including a dumping conveyance mounted on a trackway and having a frame structure including a transverse forward end portion and a drop bottom door, latch means for holding the door closed and movable -to release the same for dropping, an operating member for said latch means above the lower edge of the transverse forward end portion in the same longitudinal upright plane as said operating member, and means mounted at the trackway and movable into operative engagement with said operating member above the lower edge of said frame end portion and upwardly of the lateral confines of said frame structure for releasing the latch means when the conveyance reaches a predetermined position in the trackway.

14. In conveying mechanism including a drop bottom mine car mounted on a track and having side-sill means with transverse end-sill structures connected therewith and cooperating to form a load-supporting car-frame structure, a drop door within the frame structure for supporting at least a part of the car lading, the combination of a latch for supporting a free edge portion of said door when closed, said latch having its lowest portion when in door supporting position above the portion of the lower edge of the end-sill structure lying in the same longitudinal upright plane, means mounting said latch for movement to release the door for dropping. said latch having an actuating portion above said lower edge of the end-sill structure and accessible from beneath the car when the door is closed, and means mounted in the track for direct engagement with said actuating portion from beneath the car to release said latch.

15. In conveying mechanism including a drop bottom mine car adapted to be mounted on a track and having a lading body including wall structures with side-sill means and transverse end-sill structures connected therewith and cooperating to form a load-supporting car-frame structure for the wall structures, a drop door within the frame structure for supporting at least a part of the car lading, the combination of latch means on the car for supporting a free edge portion of said door when closed and movable to release the door for dropping, said latch means being so constructed and arranged that no part of its extends below the portion of the adjacent car frame structure lying in the same upright longitudinal plane, and contact means for moving said latch means to release the door for dropping, said contact means including a part carried by the car and a second part fixed relative to the track and operative upon engagement of said parts to move the latch means to release the door, said first-mentioned contact part being arranged entirely within a shielded area between upright planes at the outer edges of the side-sill means and along the outer faces of the wall structures, and the second contact part being movable into said shielded area into engagement with said first part.

16. In conveying mechanism, a frame structure having a lading bottom including a drop bottom door, latch means for holding the door closed and movable to release the same for dropping, said latch means being located wholly above the horizontal plane of the upper lading surface of the lowest portion of said drop bottom door in closed position and wholly above the horizontal plane of the portion of the frame structure which lies substantially inthe same longitudinal vertical plane as the latch means, and said latch means being located between the door and the frame structure in position for protection from injury and from accidental release in abnormal conditions, said latch means having an actuating portion above the lower edge of the portion of the frame structure which lies substantially in the same longitudinal vertical plane as the latch means and located substantially beneath the conveyance and accessible from under the conveyance for movement of the latch means to a released position automatically during rectilinear movement of the conveyance, and means located outside said conveyance and at least in part beneath the same and movable into operative engagement with the latch actuating portion for moving said latch means to release the door for droppin 17. In conveying mechanism, the combination of a dumping conveyance having a frame structure, a lading bottom including a drop bottom door, latch means for holding the door closed and movable to release the same for dropping, said latch means having an actuating portion connected therewith and in a shielded area above the lower edge of the frame structure and accessible from beneath the conveyance, and latch tripping mechanism being mounted in position beneath the conveyance and movable into said shielded area to engage said actuating portion 01. the latch means above the lower edge of the frame structure to release the latch means automatically during rectilinear movement of the conveyance.

18. In a dumping conveyance, a frame structure having a lading bottom including a drop bottom door, latch means for holding the door closed and movable to release the same for dropping, said latch means being located wholly above the horizontal plane of the upper lading surface of the lowest portion of said drop bottom door in closed position and wholly above the horizontal plane of the portion of the frame structure which lies substantially in the same longitudinal vertical plane as the latch means, and said latch means being located between the door and the frame structure in position for protection from injury and from accidental release in abnormal conditions, said latch means comprising a latch member having a portion arranged for latching engagement with the door, a second portion directly on the latch member and spaced downward directly below the engaging portion in position for accessibility from beneath the conveyance for movement of said latch member to release the door for dropping during rectilinear movement of the conveyance, and means located outside said conveyance and beneath the conveyance and arranged for direct engagement with the lower portion of the latch member for moving said latch member to release the door.

19. In conveying mechanism including a conveyance mounted on a trackway for movement therealong and including a frame structure with transverse end portions and a drop bottom door,

latch means for holding the door closed, and tripping mechanism for releasing the latch means, said tripping mechanism including means mounted in the trackway for operating movement upwardly therefrom into actuating relation with the latch means, yieldable means tending to urge said tripping means upwardly, and means on the conveyance and operable when the conveyance reaches a predetermined position in the trackway for causing an operating action of said tripping means to release the latch means.

20. In conveying mechanism, the combination of a dumping conveyance having a frame structure, a lading bottom including a drop bottom door, and latch means for holding the door closed and movable to release the same for dropping, said latch means having an actuating portion above the lower edge of the frame structure and accessible from beneath the conveyance, latch tripping mechanism mounted beneath the conveyance for upward movement to a position above the lower edge of the frame structure for engagement with the actuating portion of the latch means, and means connected with the con veyance for actuating the latch tripping mechanism to raise the same to release the latch means and releasing the tripping mechanism for lowering movement to under the frame structure of the conveyance after release of the latch means.

21. In conveying mechanism, the combination of a trackway, a dumping vehicle mounted on the trackway and including a frame structure, a dumping door, and latch means for holding the door closed and movable to release the same for dropping, latch tripping mechanism mounted at the trackway for upward movement relative thereto and constructed for actuating the latch meanswhen said tripping mechanism is raised and to be lowered to permit the conveyance to pass thereover, and means connected with the dumping vehicle for raising the tripping mechanism to release the latch means.

22. In conveying mechanism, the combination of a trackway, a dumping vehicle mounted on the trackway and including a frame structure, a dumping door, and latch means for holding the door closed and movable to release the same for dropping, said latch means having an actuating portion wholly above the adjacent portions of the frame structure and door, latch tripping mechanism pivotally mounted at the trackway for upward swinging movement in a path substantially parallel with the trackway to a latch tripping position in engagement with the actuating portion of the latch means, and means connected with the frame structure for causing raising movement of the tripping mechanism to said tripping position to release the latch means and releasing the tripping mechanism for drop- I normally out of the path of movement of the.

vehicle, said tripping mechanism being constructed for upward movement into the path of the latch means to release the same, and means carried by one of the side sills for actuating the tripping mechanism to raise the same to said release position.

24. In conveying mechanism, the combination of a trackway, a dumping vehicle movable over said trackway, said vehicle including a frame structure having side and end sills, a dumping door arranged in the vehicle between the side sills, and latch means for holding the door closed and movable to release the same for dropping, latch tripping mechanism mounted in the trackway normally out of the path of movement of the vehicle, said tripping mechanism having a lever bar mounted for upward swinging movement to a point above the lowest portion of the door and end-sills into the path of the latch means for releasing the same, a lever arm connected with said lever bar for moving the same, and means connected with the vehicle for actuating the lever arm.

25. In conveying mechanism, the combination of a trackway, a dumping vehicle movable over said trackway, said vehicle including a frame structure having side and end sills, a dumping door arranged in the vehicle between the side sills, and latch means for holding the door closed and movable to release the same for dropping, latch tripping mechanism mounted in the trackway normally out of the path of movement of the vehicle, saidtripping mechanism having a lever bar mounted for upward swinging movement to a point above the lowest portion of the door and end sills into the path of the latch means for releasing the same, an upstanding lever arm operatively connected with the lever bar for moving the same, and means connected with the vehicle for actuating the lever arm.

26. In conveying mechanism, the combination 5 and movable to release the same for dropping,

latch tripping mechanism mounted in the trackway normally out of the path of movement of the vehicle, said tripping mechanism having a lever bar mounted for upward swinging movement to a point above the lowest portion of the door and end sills into the path of the latch means for releasing the same, an upstanding lever arm connected with the lever bar for moving the same, said lever arm having a bearing portion at the 5 upper end thereof, means connected with the vehicle for actuating the lever arm, and lostmotion means in the tripping mechanism between said bearing portion and the lever bar for relative movement thereof.

2'1. In conveying mechanism, the combination of a trackway, a, dumping vehicle movable over said trackway, said vehicle including a frame structure having side and end sills, a dumping door arranged in the vehicle between the side sills, and latch means for holding the door closed and movable to release the same for dropping, latch tripping mechanism mounted in the trackway normally out of the path of movement of the vehicle, said tripping mechanism having a lever bar mounted for upward swinging move- 5 with the lever bar for relative movement thereof, and means connected with the vehicle for actuating the lever arm.

28. In conveying mechanism, the combination of a trackway, a dumping vehicle movable over 0 said trackway, said vehicle including a frame structure having side and end sills, a dumping .door arranged in the vehicle between the side sills, and latch means for holding the door closed and movable to release the same for dropping,

a latch tripping mechanism mounted in the trackway normally out of the path of movement of the vehicle, said tripping mechanism having a lever bar mounted for upward swinging movement to a point above the lowest portion of the door and end sills into the path of the latch means for releasing the same, an upstanding lever arm, resilient means connecting said lever arm with the lever bar for relative movement thereof, and a lug fixed to the under side of the side sill spaced from 'the latch means in position to engage and actuate the lever arm.

29. In conveying mechanism, the combination of a trackway, a dumping vehicle movable over said trackway, said vehicle including a frame structure having side and end sills, a dumping door arranged in the vehicle between the side sills, and latch means for holding the door closed and movable to release the same for dropping, latch tripping mechanism mounted in the trackway normally out of the path of movement of 7 means for releasing the same, an upstanding lever arm, resilient means connecting said lever arm with the lever bar for relative movement thereof, and a lug fixed to the under side of the side sill spaced from the latch means in posiof a trackway, a dumping vehicle movable over tion to engage and actuate the lever arm, said lug h ving a gradually sloping under side at the forward end portion thereof for raising the lever bar and having an abrupt shoulder at the rear end thereof for quick release of the lever bar.

30. In conveying mechanism, the combination of a trackway, a dumping vehicle movable over said trackway, said vehicle including a frame structure having side and end sills, a plurality of dumping doors arranged lengthwise of the vehicle between the side sills, latch means arranged between one of said doors at an end of the car and the adjacent end sill for holding said door closed and movable to release the same for dropping, means interconnecting the doors for successive dropping thereof upon release of said latched door, latch tripping mechanism mounted in the trackway for upward movement into the path of the latch means to release the same, and means carried by the vehicle for causing actuation of the latch tripping mechanism when the vehicle reaches a predetermined position on the trackway.

31. In conveying mechanism, the combination of a movable conveyance having a drop bottom door pivotally hinged at its forward end, latch means for releasably supporting the rearward end thereof, tripping mechanism located substantially below the conveyance at the point where the door is to be released, said tripping mechanism comprising two lever arms connected together one of which extends upward and the other extending lengthwise of the conveyance and having a free end for engaging the latch means, and means mounting said arms for swinging movement, said conveyance having means rigidly attached thereto in position to engage the free end portion of said upwardly extending arm and swing the same -in a forward direction raising the free end of the other arm into position for engaging and releasing the latch means.

32. In conveyingmechanism, the combination of a movable conveyance having a drop bottom door pivotally hinged at its forward end, latch means for releasably supporting the rearward end thereof, tripping mechanism located substantially below the conveyance at the point where the door is to be released, said tripping mechanism comprising two lever arms connected together one of which extends upward and the other extending lengthwise of the conveyance and having a free end for engaging the latch means, means mounting said arms for swinging-movement, said conveyance having means rigidly attached thereto in position to engage the free end portion of said upwardly extending arm and swing the same in a forward direction raising the free. end of the other arm into position for engaging and releasing the latch means, and yieldable means connecting the upwardly extending arm with the other arm for yielding action upon a predetermined extent of movement of said other arm while permitting further movement of the upwardly extending arm.

33. In conveying mechanism, the combination of a movable conveyance having a drop bottom door pivotally hinged at its forward end, latch means for releasably supporting the rearward end thereof, tripping mechanism located substantially below the conveyance at the point where the door is to be released, said tripping mechanism comprising two lever, arms connected together one of which extends upward and the other extending lengthwise of the conveyance and having a free end for engaging the latch means, and means mounting said arms for winsing movement, said conveyance having means rigidly attached thereto in position to engage the free end portion of said upwardly extending arm and swing the same in a forward direction raising the free end of the other arm into position for engaging and releasing the latch means, said engaging means on the conveyance being attached to a side portion thereof extending lengthwise of the conveyance at one side of the door.

34. In conveying mechanism including a trackway adapted to receive a dumping conveyance thereon having a drop bottom door and latching means for holding the door closed. said latching means including an actuating portion, the combination of tripping mechanism mounted in the trackway and comprising an actuating member for turning movement in an upward direction about an axis extending transversely of the trackway to a tripping position and having a tripping portion for engagement with the latch actuating portion, and means spaced from said tripping portion for engagement by a part of the conveyance spaced from the actuating means upon movement by the conveyance along the trackway for causing said turning movement of the actuating member.

35. In conveying mechanism including a trackway adapted to receive a dumping conveyance thereon having a drop bottom door and latching means for holding the door closed, said latching means including an actuating portion, the combination of tripping mechanism mounted in the trackway and comprising an actuatingmember, means mounting said member for upward swinging movement about an axis extending transversely of the trackway to a tripping position, a lever arm arranged for actuation by the conveyance in a predetermined position on the trackway and operatively connected with the actuating member for causing movement of said memher to a tripping position in engagement with the latch actuating portion, and means for yieldably supporting at least a portion of the lever arm for yielding movement relative to the actuating member.

36. In conveying mechanism including a trackway adapted to receive a dumping conveyance thereon having a drop bottom door and latch .means for holding the door closed, said latching means including an actuating portion, the

combination of tripping mechanism mounted in the trackway and comprising a lever bar mounted in the trackway for upward swinging movement about an axis extending transversely of the trackway and having a tripping portion for engaging the actuating portion of if the latch means, and an upstanding lever arm connected with the lever bar for moving the same, said lever arm having a bearing portion at the upper end thereof spaced from the tripping portion of the lever bar for engagement by a portion of the vehicle spaced from the latch means.

37. In conveying mechanism including a trackway adapted to receive a dumping conveyance thereon having a drop bottom door and latch means for holding the door closed, said latch means including an actuating portion, the combination of tripping mechanism mounted in the trackway and comprising a lever bar mounted in the trackway for upward swinging movement about an axis extending transversely of the trackway and having a tripping portion for engaging the actuating portion of the latch means, an upstanding lever arm connected with the lever bar for moving the same, said lever arm having a bearing portion at the upper end thereof spaced from the tripping portion of the lever bar for engagement by a portion of the vehicle spaced from the latch means, and yieldable lost-motion -means in the tripping mechanism between said bearing portion and the lever bar for relative movement thereof.

38. In conveying mechanism, the combination of a movable conveyance having a frame structure and a drop bottom door, latch means supporting an edge of said door for securing the door in closed position and movable to release the same for dropping, said latch means being located wholly above the horizontal plane of the upper lading surface of the lowest portion of said drop bottom door in closed position and wholly above the horizontal plane of the portion of the frame structure which lies substantially in the same longitudinal vertical plane as the latch means, and means for lifting said edge free from support on the latch means for release of the latch means therefrom, and means operable above said horizontal plane of the portion of the frame located wholly above the horizontal plane of the upper lading surface of the lowest portion of said drop bottom door in closed position and wholly above the horizontal plane of the portion of the frame structure which lies substantially in the same longitudinal vertical plane as the latch means, means for lifting said edge free from support on the latch means for release of the latch means therefrom, and means operable above said horizontal plane of the portion of the frame structure for moving the latch means from supporting position after lifting of the door therefrom.

40. In conveying mechanism, the combination of a movable conveyance having a drop bottom door, said door having a rearward projection thereon, latch means for supporting the door including a latch member having opposed portions disposed on opposite sides of said projection 

